The present invention concerns a device for controlling the binding of pressed material in the form of parallelepiped bales. The disposition of the invention described herein-below concerns, by way of example, the forming of bales of straw or fodder, but can also apply to any similar material and particularly any kind of binding material.
In an agricultural press, the binding operation is generally carried out at the moment of forming the bale, the binding material being previously placed at the inlet of the bale case, between a needle through which the binding material is delivered and a knotting device, and is displaced progressively with the pressing of the straw or fodder in the bale case When the bale is completed, the binding material thus extends practically over three sides of the bale (two longitudinal sides and its front end side) and the needle brings back the initial end of binding material towards the knotting device in order to complete the last side and finish the loop by tying a knot.
It should be recalled that these operations are carried out to the rear of an agricultural tractor automatically while the operator drives the tractor along the windrow to be baled. It is thus necessary to advise the driver of the tractor rapidly of any defect appearing in the bundling or baling operation, in order to prevent him from wasting time, on the one hand, in bundling the bales which will not be knotted and, on the other hand, once he has noticed the defect, from again bundling bales that have not been knotted.
The most current bundling defect is provoked by incorrect operating of the closing of the loop by knotting or by another joining method. Faulty bundling arises either through the absence of binding material in the system, or through the absence of a knot.
Binding material detection devices exist whose object is to test the presence of the knot tied and to emit a defect signal if the knot is absent or untied at the time of the test. These devices comprise a finger which is inserted between the bale and the binding material and which constitutes an obstacle to the passage of the rear vertical strand of the loop, this finger being retractable in the case when the loop resists the spring force maintaining the finger on the path of the binding material. The introduction of this finger under the binding material operates in known devices in several ways.
In certain devices, the finger and its control members belong to the automation of the press baler and their operation is integrated in the operating cycle of the machine. These dispositions cannot be installed separately on presses other than those for which they are intended.
In other devices, the arm is shaped in such a way as to be progressively overmounted laterally by the binding material, progressively as the shaping of the bale advances. Its passage under the binding material is often uncertain since numerous factors, such as the quality of the binding material and the dirt accumulation of the various members prohibit reliable functioning of the binding material detection device.
In any case, even in the respect of correct functioning of these devices, the defect is detected too late, i.e. at the end of making up of the bale, so that the intervention of the operator can only correct the incorrect functioning for the following bales. There remains, in this case, at least one faulty bale requiring re-knotting which is time wasted.